Hi,
Have you tried to identify those machines? Specific operating system clients are affected?
Are they in the same group?
Need to troubleshoot this issue further.
Create a new group and place affected 2-3 clients in that group.
Enable Sylink debug on those 2-3 client machines & collect the logs.
How to enable sylink logging:
1. From SEP UI->Help and Support->Troubleshooting->Debug Logs->Client Management->Edit Debug log settings->check 'Debug On'
2. Add registry entry "DumpSylink"="C:\\Sylink.log" to "HKLM\Software\Symantec\Symantec Endpoint Protection\SMC\SYLINK\Sylink"
3. Restart smc service.
Attach collected logs here.